Connecting structure of flexible printed circuit board to printed circuit board

ABSTRACT

The present invention provides a simple connecting structure of flexible printed circuit board to printed circuit board in which when connecting a flexible printed circuit board to a printed circuit board, the positioning thereof can be made easily, the connection therebetween can be made smoothly and rigidly, and further the assembling time can be reduced. Patterns  6  and  7 , respectively, on a flexible printed circuit board  4  and a printed circuit board  1  are to be aligned and connected with each other by soldering. An elongate hole  2  is bored in the vicinity of and along the edge portion  1   a  in a connecting part of the printed circuit board  1 , and two rectangular holes  3  communicating with the elongate hole  2  are formed toward the opposite direction of the edge portion  1   a  in both longitudinal end portions of the elongate hole  2 , while two cut portions  5  for controlling insertion depth are provided on both ends of the connecting edge of the flexible printed circuit board  4 . The leading edge portion  4   a  of the flexible printed circuit board  4 , which is left between the cut portions  5 , is bent downward, and the bent portion is inserted into the elongate hole  2  and the rectangular holes  3  of the printed circuit board  1  to position the flexible printed circuit board  4 , and then the patterns  6  and  7 , respectively, on the flexible printed circuit board  4  and the printed circuit board  1  are connected by soldering  10.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a connecting structure of flexible printed circuit board to printed circuit board in which patterns on a flexible printed circuit board are aligned to patterns on a printed circuit board to connect the flexible printed circuit board and the printed circuit board by soldering.

2. Description of the Prior Art

There has conventionally been known a connecting structure of this kind in which patterns 104 on a flexible printed circuit board 103 are aligned to patterns 102 on a printed circuit board 101 to connect the patterns 102 and 104 by soldering 105 as shown in FIG. 3. However, the patterns 104 on the flexible printed circuit board 103 are aligned to the patterns 102 on the printed circuit board 101 in hands, resulting in a problem in that hand movement, etc. can make the positioning and therefore the connection between the patterns 102 and 104 by the soldering 105 difficult.

In FIG. 4 is shown a first prior art. The connecting apparatus for flexible circuit boards according to this prior art is adapted, as shown in FIG. 4, to provide a plurality of longitudinal slit portions 212 in one end portion of a flexible circuit board 210, and to form bent portions 213 in the outside or inside of the slit portions 212. The bent portions 213 are engaged with engaging holes 211 d formed in a rigid circuit board 211 to position conductor patterns 210 b on the flexible circuit board 210 against conductor patterns 211 b on the rigid circuit board 211 (refer to Japanese Utility-Model Laid-Open Publication No. Sho 61-114877 for example).

However, the arrangement above suffers from a problem in that when the flexible circuit board 210 is lifted upward, the bent portions 213 can easily drop out of the engaging holes 211 d.

In FIGS. 5 (a) and 5 (b) is shown a second prior art. The mounting structure for conductive members according to this prior art is adapted, as shown in FIGS. 5 (a) and 5 (b), to provide an engaging hole 303 in a circuit board 301. One end side of a flexible circuit board 302 is divided into three portions by making two slits 305 respectively therebetween, and the central one is bent downward to form an engaging portion 306 consisting of first and second engaging portions 306 a and 306 b to be positioned on the upside surface of the circuit board 301 and a third engaging portion 306 c to be positioned on the underside surface of the circuit board 301. Then, the third engaging portion 306 c is passed under the circuit board 301 through the engaging hole 303 so that the flexible circuit board 302 is fixed to the circuit board 301 in a sandwiching manner, and connecting parts 307 in the end portion of the flexible circuit board 302 are connected to electrode patterns 304 on the circuit board 301 by soldering 308 (refer to Japanese Patent Laid-Open Publication No. 2002-270978 for example).

However, the arrangement above suffers from a problem in that part of the electrode patterns 304 should also be formed on the underside surface of the circuit board 301, that is, the circuit board 301 should be double-sided.

In FIGS. 6 (a) and 6 (b) is shown a third prior art. The mounting structure for conductive members according to this prior art is adapted, as shown in FIGS. 6 (a) and 6 (b), to provide an engaging hole 403 in a circuit board 401. The vicinity of one end portion of a flexible circuit board 402 is bent perpendicularly to the extended direction over the entire width to provide a convexly projecting engaging portion 405. The engaging portion 405, which has a height greater than the thickness of the circuit board 401, comprises a projecting portion 406 a having a width equal to or smaller than the lateral width of the engaging hole 403 and a lock portion 406 b formed on the top of the projecting portion 406 a and having a width greater than the lateral width of the engaging hole 403. Thus, once the engaging portion 405 is fitted into the engaging hole 403, the lock portion 406 b is to be caught on the edge of the engaging hole 403 so that the flexible circuit board 402 is fixed to the circuit board 401. Then, connecting parts 407 in the end portion of the flexible circuit board 402 are connected to electrode patterns 404 on the circuit board 401 by soldering 408 (refer to Japanese Patent Laid-Open Publication No. 2002-270979 for example).

However, the arrangement above suffers from a problem in that the engaging portion 405 should be formed in a downwardly projecting downward from the flexible circuit board 402, which complicates the shape of the flexible circuit board 402.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of the above-described problems, and an object thereof is to provide a simple connecting structure of flexible printed circuit board to printed circuit board in which when connecting a flexible printed circuit board to a printed circuit board, the positioning thereof can be made easily, the connection therebetween can be made smoothly and rigidly, and further the assembling time can be reduced.

The present invention has been proposed to solve the above-described problems, and the invention according to claim 1 provides a connecting structure of flexible printed circuit board to printed circuit board in which patterns on a flexible printed circuit board are aligned to patterns on a printed circuit board to connect the flexible printed circuit board and the printed circuit board by soldering, characterized in that an elongate hole is bored in the vicinity of and along an edge portion in a connecting part of the printed circuit board, and rectangular holes communicating with the elongate hole are formed toward the opposite direction of the edge portion in both longitudinal end portions of the elongate hole, while cut portions for controlling insertion depth are provided on both ends of the connecting edge of the flexible printed circuit board, a leading edge portion of the flexible printed circuit board, which is left between the cut portions, being bent downward, and that the bent portion is inserted into the elongate hole and the rectangular holes of the printed circuit board to position the flexible printed circuit board, and then patterns on the flexible printed circuit board and patterns on the printed circuit board, which face each other, are connected by soldering.

The invention according to claim 2 provides a connecting structure of flexible printed circuit board to printed circuit board in which patterns on a flexible printed circuit board are aligned to patterns on a printed circuit board to connect the flexible printed circuit board and the printed circuit board by soldering, characterized in that an elongate hole is bored in the vicinity of and along a edge portion in a connecting part of the printed circuit board, and cut portions for controlling insertion depth are provided on both ends of the connecting edge of the flexible printed circuit board, the leading edge portion of the flexible printed circuit board, which is left between the cut portions, being bent downward, and that the bent portion is inserted into the elongate hole of the printed circuit board to position the flexible printed circuit board, and then patterns on the flexible printed circuit board and patterns on the printed circuit board, which face each other, are connected by soldering.

The invention according to claim 3 is characterized in that rectangular holes communicating with the elongate hole are formed toward the edge portion in both longitudinal end portions of the elongate hole of the printed circuit board, the leading edge portion of the flexible printed circuit board, which is left between the cut portions, being inserted into the elongate hole and the rectangular holes of the printed circuit board.

The invention according to claim 4 is characterized in that tapered cut portions which narrow toward the connecting edge are provided on both ends of the leading edge portion of the flexible printed circuit board, which is left between the cut portions.

In accordance with the invention according to claim 1, the leading edge portion of the flexible printed circuit board, which is left between the cut portions, is bent downward to be inserted into the elongate hole and the rectangular holes of the printed circuit board, which allows the flexible printed circuit board to be positioned against the printed circuit board easily. It is also possible to connect the boards smoothly and rigidly with such a simple structure, and further to reduce the assembling time. In particular, the leading edge portion of the flexible printed circuit board, which is left between the cut portions, is inserted into the elongate hole and the rectangular holes of the printed circuit board in a curved manner, which allows the leading edge portion to be held and connected rigidly.

In accordance with the invention according to claim 2, the leading edge portion of the flexible printed circuit board, which is left between the cut portions, is bent downward to be inserted into the elongate hole of the printed circuit board, which allows the flexible printed circuit board to be positioned against the printed circuit board easily. It is also possible to connect the boards smoothly and rigidly with such a simple structure, and further to reduce the assembling time.

In accordance with the invention according to claim 3, the leading edge portion of the flexible printed circuit board, which is left between the cut portions, is inserted into the elongate hole and the rectangular holes of the printed circuit board in a curved manner, which allows the leading edge portion to be held and connected rigidly.

In accordance with the invention according to claim 4, the tapered cut portions are provided in the leading edge portion of the flexible printed circuit board, which is left between the cut portions, which allows the leading edge portion left between the cut portions to be inserted into the elongate hole or the elongate hole as well as the rectangular holes of the printed circuit board smoothly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a connecting structure of a flexible printed circuit board to a printed circuit board according to a first embodiment, where FIG. 1 (a) is a plan view showing the state before the flexible printed circuit board is connected to the printed circuit board, FIG. 1 (b) is a plan view showing the state where the flexible printed circuit board is connected to the printed circuit board, and FIG. 1 (c) is a vertical cross-sectional view of the state shown in FIG. 1 (b);

FIG. 2 is a plan view of a connecting structure of a flexible printed circuit board to a printed circuit board according to a second embodiment, showing the state before the flexible printed circuit board is connected to the printed circuit board;

FIG. 3 shows a conventional connecting structure of a flexible printed circuit board to a printed circuit board, where FIG. 3 (a) is a plan view thereof and FIG. 3 (b) is a vertical cross-sectional view thereof,

FIG. 4 is a plan view of a conventional connecting apparatus for flexible printed circuit boards;

FIG. 5 shows a conventional connecting structure for conductive members, where FIG. 5 (a) is a perspective view showing the state before the members are connected and FIG. 5 (b) is a perspective view showing the state where the members have been connected; and

FIG. 6 shows another conventional connecting structure for conductive members, where FIG. 6 (a) is a perspective view showing the state before the members are connected and FIG. 6 (b) is a perspective view showing the state where the members have been connected.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of connecting structures of flexible printed circuit board to printed circuit board according to the present invention will hereinafter be described with reference to the accompanying drawings.

FIG. 1 shows a connecting structure of a flexible printed circuit board to a printed circuit board according to a first embodiment, where FIG. 1 (a) is a plan view showing the state before the flexible printed circuit board is connected to the printed circuit board, FIG. 1 (b) is a plan view showing the state where the flexible printed circuit board is connected to the printed circuit board, and FIG. 1 (c) is a vertical cross-sectional view of the state show in FIG. 1 (b).

In the connecting structure of the flexible printed circuit board to the printed circuit board according to the first embodiment, as shown in FIG. 1 (a), an elongate hole 2 is bored in the vicinity of and along an edge portion 1 a in a connecting part of a printed circuit board 1, and two rectangular holes 3 communicating with the elongate hole 2 are formed toward the opposite direction of the edge portion 1 a in both longitudinal end portions of the elongate hole 2, while two cut portions 5 for controlling insertion depth are provided on both ends of the connecting edge of a flexible printed circuit board 4.

As shown in FIGS. 1 (b) and 1 (c), the leading edge portion 4 a of the flexible printed circuit board 4, which is left between the cut portions 5, is bent downward, and the bent portion is inserted into the elongate hole 2 and the rectangular holes 3 of the printed circuit board 1 to position the flexible printed circuit board 4, and then patterns 6 on the flexible printed circuit board 4 and patterns 7 on the printed circuit board 1, which face each other, are connected by soldering 10. It is preferred that the width of the elongate hole 2 of the printed circuit board 1 is approximately the same as the thickness of the flexible printed circuit board 4.

In accordance with the first embodiment, the leading edge portion 4 a of the flexible printed circuit board 4, which is left between the cut portions 5, is bent downward to be inserted into the elongate hole 2 and the rectangular holes 3 of the printed circuit board 1, which allows the flexible printed circuit board 4 to be positioned against the printed circuit board 1 easily. It is also possible to connect the boards smoothly and rigidly with such a simple structure, and further to reduce the assembling time. In particular, the leading edge portion 4 a of the flexible printed circuit board 4, which is left between the cut portions 5, is inserted into the elongate hole 2 and the rectangular holes 3 of the printed circuit board 1 in a curved manner, which allows the leading edge portion 4 a to be held and connected rigidly.

FIG. 2 is a plan view of a connecting structure of a flexible printed circuit board to a printed circuit board according to a second embodiment, showing the state before the flexible printed circuit board is connected to the printed circuit board. It is noted that components and portions identical with those of the foregoing first embodiment will be designated with the same numeral references to be described.

In the connecting structure of the flexible printed circuit board to the printed circuit board according to the second embodiment, as shown in FIG. 2, two rectangular holes 8 communicating with the elongate hole 2 are formed toward the edge portion 1 a in both longitudinal end portions of the elongate hole 2 of the printed circuit board 1. Further, two tapered cut portions 9 which narrow toward the connecting edge are provided on both ends of the leading edge portion 4 a of the flexible printed circuit board 4, which is left between the cut portions 5.

The leading edge portion 4 a of the flexible printed circuit board 4, which is left between the cut portions 5, is bent downward, and the bent edge portion 4 a is inserted into the elongate hole 2 and the rectangular holes 8 of the printed circuit board 1 to connect the patterns 6 on the flexible printed circuit board 4 and the patterns 7 on the printed circuit board 1 by soldering.

Therefore in accordance with the second embodiment, the leading edge portion 4 a of the flexible printed circuit board 4, which is left between the cut portions 5, is inserted into the elongate hole 2 and the rectangular holes 8 of the printed circuit board 1 in a curved manner, which allows the leading edge portion 4 a to be held and connected rigidly. Further, the tapered cut portions 9 are provided in the leading edge portion 4 a of the flexible printed circuit board 4, which is left between the cut portions 5, which allows the leading edge portion 4 a left between the cut portions 5 to be inserted into the elongate hole 2 and the rectangular holes 8 of the printed circuit board 1 smoothly.

It will be appreciated that the foregoing first and second embodiments are not restrictive to the rectangular holes 3 and 8 on both longitudinal ends of the elongate hole 2, but may be provided with the elongate hole 2 simply, or that the elongate hole 2 may be communicated with holes having another shape such as circular holes that are provided on both longitudinal ends of the elongate hole 2. 

1. A connecting structure for connecting a first flexible printed circuit board to a second printed circuit board with patterns on the first flexible printed circuit board aligned with patterns on the second printed circuit board for soldering together the first and second printed circuit boards, wherein an elongate hole is bored in the vicinity of and along an edge portion in a connecting part of the second printed circuit board, and rectangular holes communicating with said elongate hole are formed toward the opposite direction of the edge portion in both longitudinal end portions of said elongate hole, while cut portions for controlling insertion depth are provided on both ends of the connecting edge of the first printed circuit board, a leading edge portion of the first printed circuit board, which is left between said cut portions, being bent downward, and wherein: said bent portion is inserted into said elongate hole and said rectangular holes of the second printed circuit board to position the first printed circuit board, and patterns on the first and second printed circuit boards, which face each other, are connected by soldering.
 2. A connecting structure for connecting a first flexible printed circuit board to a second printed circuit board with patterns on the first flexible printed circuit board aligned with patterns on the second printed circuit board for soldering together the first and second printed circuit boards, wherein an elongate hole is bored in the vicinity of and along an edge portion in a connecting part of the second printed circuit board, and cut portions for controlling insertion depth are provided on both ends of the connecting edge of the first printed circuit board, a leading edge portion of the first printed circuit board, which is left between said cut portions, being bent downward, and wherein: said bent portion is inserted into said elongate hole of the second printed circuit board to position the first printed circuit board, and patterns on the first and second printed circuit boards, which face each other, are connected by soldering.
 3. The connecting structure according to claim 2, wherein rectangular holes communicating with said elongate hole are formed toward the edge portion in both longitudinal end portion of said elongate hole of the second printed circuit board, the leading edge portion of the first printed circuit board, which is left between said cut portions, being inserted into said elongate hole and said rectangular holes of the second printed circuit board.
 4. The connecting structure according to claim 2, wherein tapered cut portions which narrow toward the connecting edge are provided on both ends of the leading edge portion of the first printed circuit board, which is left between said cut portions.
 5. The connecting structure according to claim 3, wherein tapered cut portions which narrow toward the connecting edge are provided on both ends of the leading edge portion of the first printed circuit board, which is left between said cut portions. 